Duplicating pad or roll and method for its use



April 4, 1939. J. BJoRKsTEN 2,153,324

` DUPLICATING PAD 0R RoLL AND` METHOD Fon d1'1s USE Filed May 23,4 1938 Patentedv Apr. '4,31 E

UNITED VSTATES.

PATENT or-'ElcE DnrucA'rrNG PAD on. nou. AND minion Foa rrs Usa .mimi Bim-men, chica, n1., minor .m mm.

Incorporated, Chicago, Ill., a corporation o! Anuman my 2s, 193s, serai No. 20am.

A7 emma (ci. 4121.6)

This invention relates to a duplicating pad or roll and to a method of duplicating and particularly to a hectograph pad or roll and a method of hectograph duplicating. "l vMore particularly this invention is directed to the production .and use of pads orrolls having a duplicating surface of a composition compris-- ing anl acrylate resin.

An object of the invention is to provice a du- 10 plicating composition which will remain nexi-v ble, resilient'and ink-absorbent over an extended .period of time.

Another object is to provide a duplicating com-v position which does not require storage before marketing. Y

Other objects and advantages of this invention will become apparent as the following detailed description progresses, reference being made to,

the accompanying drawing, in which Fig. 1 is a perspective view oi a duplicating roll embodyingthe invention.

Fig. 2 is a section taken' along line 2 -2` of Fig.4 1. 4 Fig. 3 isa perspective view of a duplicating pad embodying the invention. f Referring to Figs. 1v and-2, the reference char- .acter I designates a backing of a flexible, strong sheet material, such as cotton, covered with a hectogrph duplicating composition 2 comprising an acry ate resin. 1

so 'In Fig. a. theta-cking 1s shown at la and the hectograph mass is shown at 2a. A preferred embodiment! of the invention a flexible, strong sheet material covered with a film of a solid polymerized acrylic acid ester con- 'taining a waterand alcohol soluble plasticlzer o f such character and in such amount as to make the composition flexible, resilient and highly ab-. sorbent, but not-inl such amount asfto make the composition so weak that it will lbreak or teark 40`during normal commercial use. I Acrylate resins suitable for this process may be prepared by lpolymerization-of acrylic acid-and ital-derivatives by heating them in the presence of suitable catalysts, such as oxygen or organic peroxides. Afgreat number of processes are known to the art, and any of theseimethods can be adapted to preparation of the acrylate materials contemplated in this invention.

. When acrylic' acid and its derivatives are lbeing polymerized, the condensation'process proceeds gradually. By interrupting Athe process after different lengths oi time, acrylate resins of difierent degrees of polymerization may be obtained.

A method for such control of the degree of poly- A merization of the iinished product is for example character of the acrylate or methacrylate derivatives involved. So, for example, are acrylatevde- `10 rivatives in general softer and more plastic than the corresponding methacrylate derivatives. 'I'he presence of long aliphatic sideI chains also tends to increase softness and plasticity. This is further influenced by the nature of the solvent pres- 15 ent during the polymerization process, and by the concentration thereof, and also by the temperature during the polymerization. M

It is thus apparent that so many factors iniiuenee the properties'of the polymerization prod 20 uct, that it would be very dimcultfto state any general rules. If the acrylate or methacrylatev lpolymer is too low, it is an oil. or too so'ft for the application now contemplated, and if it is too high it will befequally unsuitable because of fail- 25 lureto hold the necessary quantities of plasticizer.

To obtain anacrylate or methacrylate polymer i of suitable characteristics from the different, raw .g materials possible, it is therefore necessary to takeout and test samplesduring the polymeriza- 30 tion reaction, and thus to determine at what point the polymerization sh'ould .be interrupted at any particular set of conditions. -A suitable procedure is indicated by thev British Patent 374,436 (1931) to Rohm and Haas A-G. The polymerization is 35 carried out in an emulsion of the'acrylate material in water with sulphonated castor oil as emulsifying agent. The material is heated in a closed vessel with 1% or a perioxide catalyst. At

fanyf time of the reactlon,samples may be taken 40' out, andthe reaction in these samples terminated by the addition of cold water. The sam'ples thus obtained' may be ted for. suitability for use in connection with the presentinvention by:

I. Dissolving them in five timesJ their weight of 45 ethyl acetate, adding twice their own weight of glycerine, evaporating the ethyl acetate, and testlng' the resultant composition for properties as l a duplicating composition, by methods known to the art. 50

, II. By leaving-thesample resinover night in contact with one-half to four times its weightof dimethoxy tetra glycol. and'testing the resultant composition for duplicating properties.

once the optimum timev of polymerization has 56 D been established for a given acrylate or methacrylate material or reaction mixture, it is easy to manufacture a larger quantity of polymer of the desired qualities.

In the above instances the materials of desired properties were obtained by starting from unpolymerized material, and arresting the polymerizationprocess at the point where a material of desired properties was obtained.

Obviously, materials of similar properties may be obtained by starting from highly polymerized materials and de-polymerizing these, for example, by saponitlcation, until polymers of the desired properties have been arrived at. Suitable methods for stepwise controlled saponication of acrylate or methacrylate resins are disclosed in the British Patent 470,867 to the Rohm and Haas Company.

In order that the invention may be more clearly understood the following speciiic examples are given wherein the proportion and parts set out are all by weight: v

Example I Parts A 10% solution of polymerized acrylate ester in ethyl acetate, sold by the Resinous Products Co., under the trade name of Acryloid C-10 Glycerin 2 Water l/z lAcryloid B-'l Glycerin 1 Water 0.1

Exampley III Parts A 10% solution of polymerized acrylate ester in ethyl acetate, sold by the Resinous Products Co. under the trade name of Acryloid C10 10 Butyl carbitnl 3 Water 1,5

Example IV Parts "Ihe solid acrylate resin obtained by evaporation of the above named solution Acryloid C-10" '7 Dimethoxy tetra glycol 1 It is to be understood, of course, that the foregoing examples are merely illustrative and that the invention is to be in nowise limitedV thereby,

since obviously various proportions and ingre-V dients employed may be resorted to'without departure from the spirit of the invention. I

In general, the plasticizer is used in amounts of one half to two and one half times the weight 2,1sa,sa4

of the solid acrylate or methacrylate resin, and the waterin amountsoi 0 to 35% of tie plas-V ticizer. However, variations are permissible to suit specic conditions, and depending on the molecular weight and character of the resin employed. Generally, the lower molecular resins are capable of holding a higher percentage of plasticizer than the more high molecular polymers, and the resins of the. acrylate series more than those of the methacrylate series.

In the manufacture of duplicating pads or rolls, the compositions of the examples are coated on a ilexible strong backing such as cotton cloth. On evaporation of the volatile solvent a thin, tough, resilient and highly ink absorbent duplicating illm is left secured to the backing.

The resulting duplicating pad or roll' is used for making copies according to the ordinary hectograph process substantially as follows: A design formed by water or alcohol soluble dye is applied to a copy sheet. The design on the copy sheet in then contacted with' the duplicating composition, whereupon the design in reverse is transferred to the composition. vCopies are then made by contactingthe design of the duplicating mass with copy sheets.

While there ,has been shown and described certainembodiments of the invention, it is to be understood that it is capable of many modicat'ions. Changes, therefore, lin the construction and arrangement may be made without departing from the spirit and scope :of the invention as disclosed in the appended claims, in which it is the intention to claim all novelty inherent in .the invention as broadly as permissible, in view of the prior art.

I claim:

l. A duplicating pad or roll comprisingv an y acrylate resin.

' acrylate resin containing a water and alcohol soluble plasticizer.

4. A duplicating roll or pad comprising 4a duplicating composition containing an acrylate b contacting said design on the duplicating composition with copies to reproduce the design onthe copies in positive.

JOHAN BJORKSTEN. 

